Abstract Body (Do not enter title and authors here): Background and Aims:
Endothelial dysfunction is a hallmark of diabetic vascular complications, yet the underlying epigenetic mechanisms remain poorly understood. This study aimed to generate a high-resolution 3D genome atlas of diabetic endothelium, uncover the role of JUNB as a key architectural transcription factor, and identify RBBP6-mediated JUNB degradation as a critical mechanism contributing to chromatin disorganization and vascular dysfunction in diabetes.
Methods:
3D genome, epigenome and transcriptome in diabetic endothelium was profiled using H3K27ac HiChIP, ChIP-seq, ATAC-seq, and RNA-seq in both diabetic mouse models and human endothelial cells. JUNB overexpression and RBBP6 knockdown were performed to assess their roles in chromatin remodeling and endothelial function. Rapid immunoprecipitation mass spectrometry (RIME), co-immunoprecipitation, and ubiquitination assays were conducted to elucidate the post-translational regulation of JUNB by RBBP6.
Results:
Our analyses revealed that disruption of JUNB-centric chromatin topology is a key feature of diabetic endothelial cells. Mechanistically, hyperglycemia activates RBBP6-mediated ubiquitination and degradation of JUNB, resulting in a widespread loss of enhancer-promoter interactions critical for maintaining endothelial homeostasis. Furthermore, JUNB overexpression or RBBP6 knockdown restored enhancer-promoter interactions in gene programs essential for endothelial functions. Notably, RBBP6 knockdown recovered endothelium-dependent relaxation of aorta and ameliorated hindlimb ischemia in diabetic mice.
Conclusions:
These findings establish disruption of JUNB-dependent 3D genome organization as a fundamental mechanism underlying diabetic endothelial dysfunction and identify the RBBP6-JUNB regulatory axis as a promising therapeutic target for diabetic vascular complications.